Unify test code in bootstrap

[jyn514]

Right now, we copy paste a bunch of code in various places and it ends up with not all test suites supporting the same arguments. See for example #66458. We should refactor all these Steps to use the same logic for the flags to pass to cargo.

rust/src/bootstrap/test.rs

Lines 2448 to 2464 in 131ef95

	if !builder.fail_fast {
	cmd.arg("--no-fail-fast");
	}
	match builder.doc_tests {
	DocTests::Only => {
	cmd.arg("--doc");
	}
	DocTests::No => {
	cmd.args(&["--lib", "--bins", "--examples", "--tests", "--benches"]);
	}
	DocTests::Yes => {}
	}
	cmd.arg("--").args(&builder.config.cmd.test_args());
	// rustbuild tests are racy on directory creation so just run them one at a time.
	// Since there's not many this shouldn't be a problem.
	cmd.arg("--test-threads=1");

is an example of code that's repeated nearly verbatim 5+ times in test.rs. It would be nice to have a fn test_args(cargo: &mut Cargo) {} that we call instead of trying to keep these in sync.

Originally posted by @jyn514 in #72536 (comment)

[dotdot0]

@jyn514 Can I work on this issue?

[jyn514]

Sure :)

[dotdot0]

So what are the things need to be done. Can you guide me?

[jyn514]

@pratushrai0309 no, sorry, I don't have more time available to work on this issue. If you have specific questions about the things I wrote in the issue description I can answer those.

[dotdot0]

@jyn514 So we just have to create a function test_args with the code you have linked in the comment right??

[jyn514]

That is one part of the work, yes. There is other duplicated code I don't remember off the top of my head, glancing around test.rs should show several examples. But adding and using the function I mentioned would be a good start.

[dotdot0]

@rustbot claim